My problem is I can not find anyone selling uncoated 500d cordura. I have tried emailing OWFINC and Seattle Fabrics with no luck. I just sent an email to cordura themselves so I will see what they say.

In the mean time does anyone have a hook up, or an alternative fabric they could recommend?

The 500d cordura with the 'Light No Fray (kiss coat) coating'? Hopefully the coating would wear off after minimal use, leaving me with something closer to what I am looking for than the 330d uncoated stuff.

They also have some camo 500 denier that may be uncoated -doesn't say.

If you get some coated 500d, you could abrade the coating and get more breathability out of it. The coatings on Cordura are notoriously poor at keeping water out, due to the rough texture of the fabric, so I would gures you would have some level of moisture diffusion regardless.

I have found the 330d and 160d uncoated corduras to be pretty darn tough. I like the 160 better for the tighter weave. I have the 330 on the cuffs of my ski pants and it has held up very well.

The 420d is the old standby 7-8 oz packcloth – smoother texture than the cordura but still very durable. The 1000d cordura you are probably familiar with, but just in case, for comparison the 500d cordura is about 8 oz/sq. yd., while the 1000 is about 11. The 600d polyester is almost certainly faux cordura – that is, a textured fabric that looks like cordura but is not quite as tough. For your purposes (tough gaiters) all will do the job. The 100d will be the toughest for sure, but even going down to 330d you're getting some very tough fabric. The difference in weight will be a couple ounces or so, so it isn't a lot. if you want the absolute toughest, get the 1000d, if you want light but still rugged get the 330, if you want a compromise get the 420 or 600.

One minor factor is that the polyester will hold up to ultraviolet degradation better than the nylons will – but that likely won't matter for your use.